1. Field of the Invention
This invention is directed to the isomerization of 2-methyl-3-butenenitrile to linear pentenenitriles and more particularly to the isomerization of 2-methyl-3-butenenitrile to 3-pentenenitriles with improved selectivity using a zero-valent nickel complex as a catalyst for the isomerization.
2. Description of the Prior Art
U.S. Pat. No. 3,536,748 issued on Oct. 27, 1970 and assigned to E. I. du Pont de Nemours and Company discloses a process for the catalytic isomerization of 2-methyl-3-butenenitrile to linear pentenenitrile such as 3-pentenenitrile using a zero-valent nickel catalyst. Improvements and/or modifications to the aforesaid isomerization are also disclosed. U.S. Pat. No. 3,853,948 issued on Dec. 10, 1974 and assigned to E. I. du Pont de Nemours and Company, discloses an improved isomerization using an excess of neutral ligand over that required to form the zero-valent nickel complex. U.S. Pat. No. 3,676,481 issued on July 11, 1972 and assigned to E. I. du Pont de Nemours and Company describes the use of certain metal salts and/or tri(hydrocarbon) boron compounds as promoters for the zero-valent nickel catalysts used in the isomerization reaction. U.S. Pat. No. 3,852,329 issued on Dec. 3, 1974 and assigned to E. I. du Pont de Nemours and Company discloses a method for improving the yield of 3-pentenenitrile from the isomerization of 2-methyl-3-butenenitrile using a zero-valent nickel catalyst by initially contacting the potential reactants with a zeolite molecular sieve prior to the isomerization. Certain .pi.-allyl nickel complexes having ligands whose cone angles lie in the range of 130.degree.-170.degree. C. are disclosed as preferred catalysts for the isomerization reaction in U.S. Pat. No. 3,852,328 issued on Dec. 3, 1974 and assigned to E. I. du Pont de Nemours and Company.